linux-kernel - [tip:x86/pti] x86/usercopy: Replace open coded stac/clac with __uaccess

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Date:   Tue, 30 Jan 2018 14:35:59 -0800
From:   tip-bot for Dan Williams <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        dan.j.williams@...el.com, viro@...iv.linux.org.uk,
        keescook@...omium.org, mingo@...hat.com, mingo@...nel.org,
        hpa@...or.com, thomas.lendacky@....com
Subject: [tip:x86/pti] x86/usercopy: Replace open coded stac/clac with
 __uaccess_{begin, end}

Commit-ID:  b5c4ae4f35325d520b230bab6eb3310613b72ac1
Gitweb:     https://git.kernel.org/tip/b5c4ae4f35325d520b230bab6eb3310613b72ac1
Author:     Dan Williams <dan.j.williams@...el.com>
AuthorDate: Mon, 29 Jan 2018 17:02:44 -0800
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 30 Jan 2018 21:54:30 +0100

x86/usercopy: Replace open coded stac/clac with __uaccess_{begin, end}

In preparation for converting some __uaccess_begin() instances to
__uacess_begin_nospec(), make sure all 'from user' uaccess paths are
using the _begin(), _end() helpers rather than open-coded stac() and
clac().

No functional changes.

Suggested-by: Ingo Molnar <mingo@...hat.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-arch@...r.kernel.org
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Kees Cook <keescook@...omium.org>
Cc: kernel-hardening@...ts.openwall.com
Cc: gregkh@...uxfoundation.org
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: torvalds@...ux-foundation.org
Cc: alan@...ux.intel.com
Link: https://lkml.kernel.org/r/151727416438.33451.17309465232057176966.stgit@dwillia2-desk3.amr.corp.intel.com

---
 arch/x86/lib/usercopy_32.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 1b377f7..de34367 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -331,12 +331,12 @@ do {									\
 
 unsigned long __copy_user_ll(void *to, const void *from, unsigned long n)
 {
-	stac();
+	__uaccess_begin();
 	if (movsl_is_ok(to, from, n))
 		__copy_user(to, from, n);
 	else
 		n = __copy_user_intel(to, from, n);
-	clac();
+	__uaccess_end();
 	return n;
 }
 EXPORT_SYMBOL(__copy_user_ll);
@@ -344,7 +344,7 @@ EXPORT_SYMBOL(__copy_user_ll);
 unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from,
 					unsigned long n)
 {
-	stac();
+	__uaccess_begin();
 #ifdef CONFIG_X86_INTEL_USERCOPY
 	if (n > 64 && static_cpu_has(X86_FEATURE_XMM2))
 		n = __copy_user_intel_nocache(to, from, n);
@@ -353,7 +353,7 @@ unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *fr
 #else
 	__copy_user(to, from, n);
 #endif
-	clac();
+	__uaccess_end();
 	return n;
 }
 EXPORT_SYMBOL(__copy_from_user_ll_nocache_nozero);